Relaxers are chemical solutions used for the purpose of straightening, softening or loosening curled or wavy hair. Generally these chemical compositions contain soluble alkaline earth materials such as sodium or calcium hydroxide. Organic bases such as guanidine hydroxide are also employed as relaxers.
Sodium hydroxide, used in products referred to as “lye” relaxers, provides the longest lasting and dramatic effects. However, at a pH of about 14, solutions of sodium hydroxide have a pronounced tendency to damage the skin and hair.
Relaxers referred to as “no lye” systems have a lower pH of about 13. Nevertheless, such relaxers have the potential to weaken the hair making it extremely susceptible to breaking and further damage. For this reason, a pre-protective petroleum “base cream” is frequently applied to help protect the scalp against chemical irritation. After the hair has been chemically relaxed, a neutralizing formula may be applied to lower the pH and reduce the potential for hair breakage. Frequently, a conditioner is applied to the hair to restore some of the natural oils and proteins removed by the chemical.
“No lye” relaxers utilize the organic chemical base, guanidine, present in the form of guanidine hydroxide, as the straightening agent. The product is supplied as a two component system comprising first an aqueous solution of guanidine carbonate at or near the saturation point. The second component is a water in oil cream emulsion containing calcium hydroxide (inorganic alkaline earth hydroxide) at 3-8% typically by weight usually referred to as the “base”. Upon mixing, the guanidine carbonate component of the activator solution reacts with the base, e.g., calcium hydroxide forming guanidine hydroxide and precipitated calcium carbonate.
Guanidine hydroxide is not stable after formation and decomposes into ammonia and urea within 6-12 hours after mixing. The guanidine hydroxide elevates the pH of the product to about 13 and thereby allows for successful relaxation of the hair. Products of this type normally do not require a pre-protective application of petrolatum or similar composition. These products are typically called “no-lye products”.
The high pH relaxer compositions available today utilize very much the same chemistry in that they all rely on the generation of hydroxide to relax the hair. This high pH relaxation of the hair fiber is not without challenge to the formulator. Modern compositions contain skin protectants such as mineral oil and petrolatum, waxes, conditioning agents and humectants but the high pH of the relaxer cream base itself prevents the inclusion into the formula of ingredients that would have greater beneficial effect for the consumer. The typical relaxer base containing calcium hydroxide has a pH in the range of 11-12.5 before activation with guanidine carbonate. After activation, this pH will increase 15 fold but still, at a pH above 11 many organic and beneficial ingredients are destroyed. At this elevated pH only the most basic and chemically resistant materials survive for any length of time. While many modern products may include some organic materials in their relaxer creams or bases, the longevity and stability of these materials is very highly suspect at the pH mentioned above. As a result, many relaxers deliver poor performance and may irritate the skin if not used specifically as directed.